Mass and Weight · Unit Converter

Convert Ounce to Grain

Convert ounces to grains instantly. 1 ounce = 437.5000671308 grain — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Grain to Ounce converter for the reverse conversion.

Written by Sunith Babu L, Ph.D., Lead Engineer Reviewed by Dr. Ashok Kumar K, Ph.D.
Mass and Weight category 2 min read Published Last reviewed Updated

Units explained

Avoirdupois

Ounce

What is a ounce?

The (avoirdupois) ounce (oz) equals one-sixteenth of a pound, about 28.35 grams.

Origin of the ounce

From Latin 'uncia', meaning a twelfth part.

Where it is used

US food portions, postal weights, and boxing weight classes.

When and where it was developed

Standardized as 1/16 of the international pound from 1959.

Avoirdupois

Grain

What is a grain?

The grain (gr) equals 1/7000 of an avoirdupois pound, about 64.8 milligrams.

Origin of the grain

Based on the nominal mass of a single barley grain.

Where it is used

Ammunition and bullet mass, archery, and historical pharmacy.

When and where it was developed

Standardized through the English avoirdupois system and retained in 1959.

Ounce to Grain conversion formula

The relationship between ounces and grains:

1 oz = 437.5000671308 gr
1 gr = 0.0022857139 oz

To convert ounces to grains, multiply the value in ounces by 437.5000671308. To reverse, multiply grains by 0.0022857139.

How to use this converter

Type a value into the calculator. The result in grains updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Grain to Ounce converter for the reverse direction.

Step-by-step: convert ounces to grains

  1. Write down the value in ounces (oz).
  2. Multiply that value by the factor 437.5000671308.
  3. The product is the equivalent value in grains (gr).
  4. To reverse, multiply the grain value by 0.0022857139.

Worked examples

Example 1 — Convert 1 oz to gr:
1 × 437.5000671308 = 437.5000671308 gr

Example 2 — Convert 100 oz to gr:
100 × 437.5000671308 = 43750.0067130769 gr

Real-world example — Adjacent small-scale precision

One ounce equals 1,000 grains — the standard sub-millimeter precision conversion that materials engineers use whenever they switch between bulk material thickness specs (larger unit) and surface-finish characteristics (smaller unit).

1 oz × 437.5000671308 = 437.5000671308 gr

Real-world example — Adjacent metric sub-units

One ounce equals 1,000 grains. Engineers move between these scales constantly: PCB feature sizes in the larger unit, wire-bond diameters in the smaller.

1 oz × 437.5000671308 = 437.5000671308 gr

Ounce to Grain conversion table

Standard reference values for converting ounces to grains:

Ounce [oz]Grain [gr]
0.014.3750006713
0.143.7500067131
1437.5000671308
2875.0001342615
31312.5002013923
41750.0002685231
52187.5003356538
104375.0006713077
208750.0013426154
3013125.0020139231
4017500.0026852308
5021875.0033565385
10043750.0067130769
500218750.0335653846
1000437500.0671307693

Frequently asked questions

How many grains is 1 ounce?
1 ounce equals 437.5000671308 grain.
How do I convert ounces to grains?
Multiply the value in ounces by 437.5000671308 to get grains.
How do I convert grains back to ounces?
Multiply the value in grains by 0.0022857139, or use the Grain to Ounce converter.
How many grains is 100 ounces?
100 ounces equals 43750.0067130769 grains, because 100 × 437.5000671308 = 43750.0067130769.

Convert Ounce to other weight units

Show all Ounce conversions
Metric / SI (18 units)
Ounce to Attogram (ag) Ounce to Femtogram (fg) Ounce to Picogram (pg) Ounce to Nanogram (ng) Ounce to Microgram (µg) Ounce to Milligram (mg) Ounce to Centigram (cg) Ounce to Decigram (dg) Ounce to Gram (g) Ounce to Dekagram (dag) Ounce to Hectogram (hg) Ounce to Kilogram (kg) Ounce to Quintal (metric) (q) Ounce to Metric Ton (t) Ounce to Gigagram (Gg) Ounce to Teragram (Tg) Ounce to Petagram (Pg) Ounce to Exagram (Eg)
Avoirdupois (14 units)
Ounce to Grain (gr) Ounce to Dram (avoirdupois) (dr) Ounce to Pound (lb) Ounce to Clove (clove) Ounce to Stone (US) (st) Ounce to Stone (UK) (st) Ounce to Quarter (US) (qr) Ounce to Quarter (UK) (qr) Ounce to Hundredweight (US) (cwt) Ounce to Hundredweight (UK) (cwt) Ounce to Wey (wey) Ounce to Kilopound (kip) (kip) Ounce to Ton (short, US) (sh tn) Ounce to Ton (long, UK) (long tn)
Troy & Apothecary (10 units)
Ounce to Point (1/100 carat) (pt) Ounce to Carat (metric) (ct) Ounce to Scruple (apothecary) (s ap) Ounce to Pennyweight (dwt) Ounce to Momme (mom) Ounce to Mace (mace) Ounce to Dram (apothecary/troy) (dr ap) Ounce to Troy Ounce (oz t) Ounce to Tael (tael) Ounce to Pound (troy/apothecary) (lb t)
Indian / South Asian (6 units)
Ounce to Ratti (ratti) Ounce to Masha (masha) Ounce to Tola (tola) Ounce to Chittack (Chatank) (chittack) Ounce to Seer (Ser) (seer) Ounce to Maund (Mann) (maund)
Scientific / Atomic (9 units)
Ounce to Electron Mass (rest) (me) Ounce to MeV/c2 (MeV/c²) Ounce to Muon Mass (mµ) Ounce to Atomic Mass Unit (u) Ounce to Proton Mass (mp) Ounce to Neutron Mass (mn) Ounce to Deuteron Mass (md) Ounce to Carbon-12 Atom Mass (C-12) Ounce to Planck Mass (mP)
Astronomical (4 units)
Ounce to Lunar Mass (Moon) (M☾) Ounce to Earth's Mass (M⊕) Ounce to Jupiter Mass (MJ) Ounce to Sun's Mass (M☉)
Biblical / Ancient (14 units)
Ounce to Lepton (Biblical Roman) (lepton) Ounce to Quadrans (Biblical Roman) (quadrans) Ounce to Assarion (Biblical Roman) (assarion) Ounce to Gerah (Biblical Hebrew) (gerah) Ounce to Drachma (Biblical Greek) (drachma) Ounce to Denarius (Biblical Roman) (denarius) Ounce to Bekan (Biblical Hebrew) (bekah) Ounce to Didrachma (Biblical Greek) (didrachma) Ounce to Shekel (Biblical Hebrew) (shekel) Ounce to Tetradrachma (Biblical Greek) (tetra) Ounce to Mina (Biblical Greek) (mina) Ounce to Mina (Biblical Hebrew) (mina) Ounce to Talent (Biblical Greek) (talent) Ounce to Talent (Biblical Hebrew) (talent)
Force / Engineering (5 units)
Ounce to Poundal (pdl) Ounce to Ton (assay) (US) (AT) Ounce to Ton (assay) (UK) (AT) Ounce to Kilogram-force square second/meter (hyl) Ounce to Slug (slug)

Sources & references

Conversion factor (1 oz = 437.5000671308 gr) verified against the following authoritative sources:

Results are provided for general reference. Verify critical measurements against an authoritative standard.